This page discusses various methods on how to write an Arch Linux release to a USB drive (also referred to as "flash drive", "USB stick", "USB key", etc). The result will be a LiveCD-like system ("LiveUSB", if you will) that, because of the nature of SquashFS, will discard all changes once the computer shuts down.

How to restore the USB drive

Because the ISO image is a hybrid which can either be burned to a disc or directly written to a USB drive, it doesn't include a standard partition table.

After you install Arch Linux and you're done with the USB drive, you should zero out its first 512 bytes (meaning the boot code from the MBR and the non-standard partition table) if you want to restore it to full capacity:

# dd count=1 bs=512 if=/dev/zero of=/dev/sdx

Then create a new partition table (e.g. "msdos") and filesystem (e.g. EXT4, FAT32) using gparted, or from a terminal:

Without overwriting the USB drive

This method is slightly more complicated than writing the image directly with dd, but it does keep the drive usable for data storage. Before you begin, make sure that your USB device is formatted as either FAT32, EXT2/3/4 or Btrfs. For UEFI boot and/or interoperability with other operating systems you should use FAT32. Also, make sure that you have the syslinux package (version 4.04 or newer) installed.

1. Extract the arch folder from the ISO to the USB drive. For UEFI motherboards follow these instructions.

2. Install the Syslinux bootloader:

Warning: Be very careful where you point dd and please use the drive itself in the following commands, not the first partition. This is a very common mistake.

Note: On some distributions mbr.bin may be available as /usr/share/syslinux/mbr.bin.

If the syslinux package on your distribution is older than version 4.06, as a workaround for FAT32 filesystems (unnecessary for EXT4), the APPEND line from syslinux.cfg should also be replaced:

$ sed -i "s|../../|/arch|" syslinux.cfg

Using UNetbootin

UNetbootin can be used on any Linux distribution or Windows to copy your iso to a USB device. Unetbootin overwrites syslinux.cfg, so it creates a USB device that does not boot properly. For this reason, Unetbootin is not recommended -- please use "dd" or one of the other methids discussed in this topic.

Warning: UNetbootin writes over the default syslinux.cfg; this must be restored before the USB device will boot properly.

In /dev/sdx1 you must replace x with the first free letter after the last letter in use on the system where you are installing Arch Linux (e.g. if you have two hard drives, use c.). You can make this change during the first phase of boot by pressing Tab when the menu is shown.

On Mac OS X

To be able to use dd on your USB device on a Mac you have to do some special maneuvers. First of all insert your usb device, OS X will automount it, and in Terminal.app run:

$ diskutil list

Figure out what your USB device is called with mount or sudo dmesg | tail (e.g. /dev/disk1) and unmount the partitions on the device (i.e., /dev/disk1s1) while keeping the device proper (i.e., /dev/disk1):

$ diskutil unmountDisk /dev/disk1

Now we can continue in accordance with the instructions above (but use bs=8192 if you are using the OS X dd, the number comes from 1024*8).

It is probably a good idea to eject your drive before physical removal at this point:

$ diskutil eject /dev/disk1

On Windows

Image Writer for Windows

Download the program from http://sourceforge.net/projects/win32diskimager/ and run it. Select the arch image-file and usb stick. The Win32 Disk Imager's file browser assumes image files end with .img, so if the image file you have selected ends with .iso, you will have to type its name in manually; this difference in suffixes is simply cosmetic however, the image will be written fine regardless. Click on the write button. Now you should be able to boot from the usb stick and install Arch Linux from it.

USBWriter for Windows

Download the program from http://sourceforge.net/projects/usbwriter/ and run it. Select the arch image file, the target USB stick, and click on the write button. Now you should be able to boot from the usb stick and install Arch Linux from it.

The Flashnul Way

From a command prompt, invoke flashnul with -p, and determine which device index is your USB drive, e.g.:

C:\>flashnul -p

Avaible physical drives:
Avaible logical disks:
C:\
D:\
E:\

When you have determined which device is the correct one, you can write the image to your drive, by invoking flashnul with the device index, -L, and the path to your image, e.g:

C:\>flashnul E: -L path\to\arch.iso

As long as you are really sure you want to write the data, type yes, then wait a bit for it to write. If you get an access denied error, close any Explorer windows you have open.

If under Vista or Win7, you should open the console as administrator, or else flashnul will fail to open the stick as a block device and will only be able to write via the drive handle windows provides

Note: Confirmed that you need to use drive letter as opposed to number. flashnul 1rc1, Windows 7 x64.

The Cygwin Way

Make sure your Cygwin installation contains the dd package. Or if you do not want to install Cygwin, you can simply download dd for Windows from http://www.chrysocome.net/dd.

Place your image file in your home directory:

C:\cygwin\home\John\

Run cygwin as administrator (required for cygwin to access hardware). To write to your USB drive use the following command:

dd if=image.iso of=\\.\[x]:

where image.iso is the path to the iso image file within the cygwin directory and \\.\[x]: is your USB device where x is the windows designated letter, e.g. \\.\d:.

On cygwin 6.0 find out the correct partition with:

cat /proc/partitions

and write the ISO image with the information from the output. Example:

Warning: This will irrevocably delete all files on your USB stick, so make sure you do not have any important files on the stick before doing this.

dd if=image.iso of=/dev/sdb

dd for Windows

A GPL licensed dd version for Windows is available at http://www.chrysocome.net/dd. The advantage of this over Cygwin is smaller download. Use it as shown in instructions for Cygwin above.

Boot the entire ISO from RAM

This method uses Syslinux and MEMDISK to load the entire ISO image in RAM, so make sure you have enough RAM to hold it. Once it's done loading and you see the graphical menu you can simply remove the USB stick and maybe even use it on a different machine to start the process all over again. It also allows booting and installing Arch from (and to) the same USB stick.

1. Format the USB stick as FAT32 and create the following folders:

X:\Boot
X:\Boot\ISOs
X:\Boot\Settings

2. Copy the ISO you'd like to boot to the ISOs folder (e.g. archlinux-2013.04.01-dual.iso), and extract from the latest release (e.g. syslinux-4.05.zip):

Tip: If you want to add more distributions (Debian and Parted Magic were tested) you can edit this file. Maybe even give it a nice menu and a background image, instead of defaulting to the Arch Linux ISO. Refer to the Syslinux wiki.

3. Finally, create a *.bat file where syslinux.exe is located and run it ("Run as administrator" if you're on Vista or Windows 7):

C:\Documents and Settings\username\Desktop\install.bat

@echo off
syslinux.exe -m -a -d /Boot/Settings X:

Done.

Troubleshooting

Note: For the MEMDISK Method, if you get the famous "30 seconds" error trying to boot the i686 version, press the Template:Keypress key over the Boot Arch Linux (i686) entry and add vmalloc=448M at the end. For reference: If your image is bigger than 128MiB and you have a 32-bit OS, then you have to increase the maximum memory usage of vmalloc. (*)

Note: If you get the "30 seconds" error due to the /dev/disk/by-label/ARCH_XXXXXX not mounting, try renaming your USB media to ARCH_XXXXXX (e.g. ARCH_201302).